Shoe for medical applications

ABSTRACT

A shoe with a permanent magnet including a basic body having a magnetic North Pole and a magnetic South Pole and being elastically deformable solves the problem of realizing a shoe which is able to provide its wearer with information about the material properties and the condition of the shoe.

This claims the benefit of DE 10 2007 032 821.6 filed on Jul. 12, 2007, through PCT/EP2008/005238 filed on Jun. 27, 2008, both are hereby incorporated by reference herein. The invention relates to a shoe for medical applications as well as to an insole for a shoe.

BACKGROUND OF THE INVENTION

Diabetics, in particular, suffer from circulation problems and are especially sensitive to pressure on the skin. Such pressure loads cause pressure sores on the body that can become infected and lead to ulceration.

Shoes known from the state of the art often make use of foams. These foams become compacted over the course of time and thus cannot provide their full springy and cushioning effect. This results in areas in the shoes that can no longer provide springiness and cushioning. This can lead to pressure loads on the feet of the wearer.

Especially diabetics, whose feet easily develop ulceration, suffer the effects of these pressure loads.

SUMMARY OF THE INVENTION

Therefore, the invention is based on an objective of creating a shoe that can provide its wearer with information about the material properties and the condition of the shoe.

The invention provides a shoe with a permanent magnet, whereby said permanent magnet may include a base body having a magnetic north pole and a magnetic south pole, and whereby the base body can be elastically deformed; an insole with a permanent magnet, whereby said permanent magnet may include a base body having a magnetic north pole and a magnetic south pole, and whereby the base body can be elastically deformed.

Accordingly, a shoe or an insole comprises a permanent magnet that, whereby said permanent magnet comprises a base body having a magnetic north pole and a magnetic south pole, whereby the base body can be elastically deformed.

According to the invention, it has been recognized that an elastic permanent magnet makes it possible to generate signals that provide information about the deformation state and the elasticity properties of the permanent magnet. In quite concrete terms, it has been realized that an elastic permanent magnet can be combined with a sensor that provides the wearer of the shoe with information as to whether individual areas of the elastic permanent magnet or of its base body have become severely compacted. Such compacted areas can no longer provide their full springiness and cushioning effect and can then cause pressure sores on the feet of the wearer. Diabetics, in particular, because of their disease, do not early enough notice pain and ulcerations caused by pressure sores. Through the sensor that interacts with the permanent magnet, warning signals can be given to the wearer of the shoe, especially a diabetic person, indicating that the shoe or its sole has to be replaced. Consequently, the above-mentioned objective is achieved.

The use of an elastic permanent magnet for the production of a shoe for medical applications opens up the possibility of manufacturing shoes that are especially beneficial to health.

The permanent magnet could be positioned in the sole of the shoe. Through this concrete embodiment, the shoe can be repaired without any problem. The sole can be replaced if the shoe is worn down or has become compacted to such an extent that it can no longer provide any cushioning effect. The shoe uppers can be used again.

It is also conceivable for the elastic permanent magnet to be an integral part of the insole of the shoe. In this case as well, if the insole is worn down, it could be replaced and the shoe could continue to be used.

The permanent magnet could be positioned in the shoe in the area of the heel and/or in the area of the ball of the foot. The heel and ball areas of the foot are subject to severe pressure loads. This is why the heel and ball areas of the foot have to be especially well-cushioned. The positioning of the permanent magnet in the heel area and/or in the ball area allows monitoring of the especially critical spots of a shoe.

The base body could be made of a foam throughout which magnetically hard particles are distributed. The use of foam is especially advantageous since a base body made of foam can be elastically and reversibly deformed without any problem when pressure is applied.

Before this backdrop, it is conceivable for the foams used to be either elastomeric foams or foams made of thermoplastic elastomers or a mixture of both of these. As set forth in this application, the term elastomeric foams refers to foamed plastics that exhibit rubber-elastic behavior. These can be chemically or physically loosely crosslinked polymers that behave energy-elastically below their glass transition temperature and that are rubbery-elastic at temperatures above their glass transition temperature. The glass transition temperatures of the preferably used elastomers are 20° C. [68° F.] or less. Preferably, the employed elastomeric foams are rubbery-elastic up to their melting or decomposition temperature.

Preferably used elastomers are SBR (polystyrene butadiene rubber), NBR (nitrile-butadiene rubber), EPM (ethylene-propylene rubber), EPDM (ethylene-propylene-diene rubber), EVA (ethyl vinyl acetate), CSM (chlorosulfonyl-polyethylene rubber), VSi (silicon rubber) or AEM (ethylene-acrylate rubber) all of which can be readily processed employing molding techniques.

Preferably used thermoplastic elastomers are thermoplastic polyesters, thermoplastic polyamides, non-crosslinked thermoplastic polyolefins, partially crosslinked thermoplastic polyolefins, thermoplastic styrene polymers and especially thermoplastic polyurethanes. These materials can be readily processed employing foaming techniques.

The foams can have any desired pore size. Open-cell or closed-cell foams can be used. In the case of open-cell foams, at least some of the individual pores are in contact with each other. In the case of closed-cell foams, the pores are all isolated from each other in the polymer matrix. Typical pore sizes are in the range from 10 μm to 3 mm.

Through the use of magnetically hard particles, it is advantageously ensured that, after a base body is magnetized, it acquires permanent magnetization. Completely in contrast to magnetically soft particles, which very easily lose their magnetization, the magnetically hard particles retain their magnetization. In concrete terms, the elementary magnets are permanently oriented and thus form permanent north and south poles.

The base bodies could consist of a foam made of ethyl vinyl acetate. A foam made of this material has proven to be especially suitable for holding magnetically hard particles in a homogeneous distribution. Moreover, individual foam layers of ethyl vinyl acetate can be easily joined together by means of vulcanization or adhesion.

In order to make a sole for a shoe, three foam layers of different hardness levels could be joined together by means of vulcanization or adhesion. The foam layer facing the floor could be the hardest foam layer in order to give the sole sufficient stability.

SrFeO particles (strontium ferrite particles) could be distributed throughout the base body. This material exhibits permanent magnetization and is thus especially well-suited for the production of a permanent magnet.

Before this backdrop, it is also conceivable for NdFeB particles (neodymium iron boron particles) to be distributed throughout the base body. The magnetically hard particles exhibit a permanent magnetization after their elementary magnets have been oriented by an external permanent magnet or by a magnetic pulse.

The particles could have a mean diameter of 10 nm to 500 μm. Advantageously, particles of this size do not disturb the structure of the foam matrix. The webs between the pores are hardly influenced in terms of their stability.

Especially preferably, magnetically hard particles with a mean diameter of 0.5 μm to 5 μm could be used, since they can be dispersed in a foamable material without any problem and are distributed especially homogeneously throughout the finished foam.

A sensor can be associated with the base body. Here, it is concretely conceivable for a base body with a cuboidal, parallelepipedal or cylindrical shape to have a sensor on one of its surfaces. If the base body is configured as the sole of a shoe, it could be wedge-shaped. The sensor can detect the change in a magnetic field or the change in a magnetic field strength that results from a deformation of the elastic base body. A Hall sensor could be used as the sensor. Hall sensors are characterized by high resolution and reliability.

If the base body is configured as the sole of a shoe, the sensor could be embedded in the base body. With this approach, the sensor is effectively protected against environmental influences.

Before this backdrop, it is concretely conceivable for the elastic permanent magnet that is fitted with a sensor to be used as a pressure sensor. The sensor can detect and indicate voltage values that correspond to a change in the magnetic field of the permanent magnet. The change in the magnetic field, in turn, can be correlated with a deformation of the base body by a certain distance. If the compressibility of the base body is known, a distance-tension diagram makes it possible to draw conclusions about the force or pressure with which the base body has been deformed.

The permanent magnet described here could be produced by a method comprising the following steps:

preparation of a homogenous mixture consisting of a foamable material and of magnetically hard particles, foaming of the material, production of a finished foam, and magnetization of the magnetically hard particles by means of an external permanent magnet or a magnetic pulse.

With this method, permanent magnets can be made of foam in which magnetically hard particles are homogeneously distributed.

All of the embodiments relating to the structure of the base body as well as to the sensors likewise apply to the structure of the insole .or to orthotic insoles.

There are various ways in which to configure and refine the teaching of the present invention in an advantageous manner. Reference is hereby made, one the one hand, to the subordinate claims and, on the other hand, to the explanation below of a preferred embodiment of the invention on the basis of the drawing.

In conjunction with the explanation of the preferred embodiment of the invention on the basis of the drawing, a general explanation is also given of preferred embodiments and refinements of the teaching.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show the following:

FIG. 1 a schematic view of a permanent magnet in an unloaded state and in a state in which it is deformed as a result of pressure.

FIG. 2 a distance-tension diagram of a pressure sensor, comprising a permanent magnet of the type described here,

FIG. 3 a shoe in a schematic view in which the sole is configured as a permanent magnet, and

FIG. 4 an insole made up of two different foam layers.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a permanent magnet comprising a cylindrical base body 1. The base body 1 has a magnetic north pole 2 and a magnetic south pole 3. The base body 1 can be deformed elastically. This is schematically shown in the right-hand drawing in FIG. 1.

The base body 1 consists of a foam made of ethyl vinyl acetate in which magnetically hard particles 4 of strontium ferrite (SrFeO particles) are homogeneously distributed. These particles have a mean diameter of 0.5 μm to 5 μm. The strontium ferrite 4 was magnetized by an external permanent magnet or by a magnetic pulse in such a way that their elementary magnets are permanently oriented. Therefore, the permanent magnet 1 according to FIG. 1 exhibits permanent magnetization.

The base body 1 is made of a foam that has pores 6 that are in the range from 10 μm to 3 mm.

A sensor 5 is arranged on the circular base surface 7 of the cylindrical base body 1 according to FIG. 1. The sensor 5 is configured as a Hall sensor. The sensor 5 and the base body 1 in their entirety form a pressure sensor that can be used to detect pressures or distances ΔT.

The left-hand drawing in FIG. 1 shows the base body 1 in the unloaded state. In the unloaded state, the base body 1 forms magnetic field lines having a certain spacing. When pressure is applied to the base body 1 by a pressure (P) as shown in the right-hand drawing in FIG. 1, the structure of the field lines, especially their density, is changed. Through the change in the field lines of the magnetic field and thus in its field strength, a voltage U is generated as the sensor signal in the Hall sensor 5. The voltage U is correlated with a distance ΔT by which the base body 1 has been compressed.

Thus, a distance ΔT can be ascertained from the detected voltage.

If the compressibility of the foam of the base body 1 and the distance ΔT by which the base body 1 has been brought to a second height are known, then a compressive force that is acting on the base body 1 can be deduced. Consequently, the elastic permanent magnet described here can be used in a pressure sensor.

FIG. 2 shows a distance-tension diagram that was measured with a Hall sensor 5 of the type Allegro A 1395. The employed elastic permanent magnet comprises a base body 1 that consists of a foam made of ethyl vinyl acetate. Magnetically hard strontium ferrite particles with mean diameters in the range from 0.5 μm to 5 μm are distributed throughout the foam. The cylindrical base body 1 has a height of 4 mm and the base surfaces have a diameter of 6 mm. The poles 2, 3 are associated with the base surfaces. In the unloaded state of the base body 1, the magnetic field strength amounts to 5.5 mT (milliteslas).

FIG. 2 shows that a compression of the base body 1 by a distance ΔT that is measured in mm, is correlated with a sensor signal that is measured in mV.

The sensor signals that result when the load increases (pressure increase) as well as the sensor signals that occur when the load decreases (pressure decrease) were measured. The voltage output by the sensor 5 in mV is proportional to the distance ΔT by which the base body 1 is deformed or compressed in the axial direction. In this process, each voltage value is correlated with a deformation state of the base body 1. Therefore, by ascertaining a voltage value, it is possible to draw conclusions about the degree of deformation or compression of the base body 1.

FIG. 3 shows a shoe, especially for diabetics, with a permanent magnet comprising a base body 1 having a magnetic north pole 2 and a magnetic south pole 3. The base body 1 is elastically deformable. The permanent magnet is positioned in the sole 8. Concretely speaking, the base body 1 is configured as a sole 8. The permanent magnet is positioned in the heel area 9 as well as in the ball area 10 of the foot.

The base body 1 consists of a foam made of ethyl vinyl acetate. Magnetically hard particles 4 configured as strontium ferrite particles are distributed throughout the foam. These particles 4 have a mean diameter in the range from 0.5 μm to 5 μm. The strontium ferrite particles 4 were magnetized by an external permanent magnet or by a magnetic pulse in such a way that their elementary magnets are permanently oriented in the base body 1. Therefore, the permanent magnet according to FIG. 3 exhibits permanent magnetization. The base body 1 is made of a foam having pores 6. The diameter of the pores 6 is in the range from 10 μm to 3 mm.

A sensor 5 is arranged in the heel area 9 as well as in the ball area 10 of the foot. In their entirety, the sensors 5 and the base body 1 constitute a pressure sensor. By ascertaining voltage values, the sensors 5 can provide information as to whether the base body 1 is already compacted to such an extent that it can no longer provide a cushioning effect. The voltage values supplied by the sensors 5 give the wearer of the shoe a signal as to whether the base body 1 or the sole 8 or parts of the sole 8 are already severely deformed due to ageing or settling processes. Here, each voltage value according to FIG. 2 corresponds to a degree of deformation or compaction of the base body 1 or of the sole 8.

The sole 8 could be made up of several elastic foam layers, whereby at least one of the foam layers is the base body 1 of the elastic permanent magnet described here. The foam layers could be joined together by means of vulcanization.

FIG. 4 shows an insole for a shoe that is made up of two different foam layers 1 and 11. Here, the structure of the foam layer 1 corresponds to the base body 1 described above and is configured as an elastic permanent magnet. Hall sensors 5 are arranged in the heel area 9 as well as in the ball area 10 of the foot, and these sensors can be used to monitor the deformation of the foam layers 1 and 11.

Concerning additional advantageous embodiments and refinements of the teaching according to the invention, reference is hereby made, on the one hand, to the general part of the description and, on the other hand, to the patent claims.

Finally, it must be stated explicitly that the purely randomly selected embodiment shown here serves merely to elucidate the teaching according to the invention, but that this teaching is by no means limited to this embodiment. 

1-11. (canceled) 12: A shoe comprising: a permanent magnet including an elastically deformable base body having a magnetic north pole and a magnetic south pole; and a sensor associated with the base body for detecting a change in a magnetic field or a change in a magnetic field strength that results from a deformation of the base body. 13: The shoe according to claim 12 further comprising a sole, the permanent magnet being positioned in the sole. 14: The shoe according to claim 12 further comprising a heel, the permanent magnet being positioned in an area of the heel. and/or in the area of the ball of the foot. 15: The shoe according to claim 12 further comprising a ball area for supporting a ball of a foot, the permanent magnet being positioned in the ball area. 16: The shoe according to one of claim 12 wherein the base body is made of a foam throughout which magnetically hard particles are distributed. 17: The shoe according to claim 12 wherein the base body comprises a foam made of ethyl vinyl acetate. 18: The shoe according to claim 12 wherein the base body comprises an elastomer from the group consisting of SBR (polystyrene butadiene rubber), NBR (nitrile-butadiene rubber), EPM (ethylene-propylene rubber), EPDM (ethylene-propylene-diene rubber), EVA (ethyl vinyl acetate), CSM (chlorosulfonyl-polyethylene rubber), VSi (silicon rubber) or AEM (ethylene-acrylate rubber). 19: The shoe according to claims 12 wherein SrFeO particles are distributed throughout the base body. 20: The shoe according to claims 12 wherein NdFeB particles are distributed throughout the base body. 21: The shoe according to claims 12 wherein the sensor is embedded in the base body. 22: A shoe according to claims 12 further compring a sole, the sensor giving the wearer of the shoe a signal as to whether the base body or the sole or parts of the sole are already severely deformed due to ageing. 23: An insole comprising: a permanent magnet including an elastically deformable base body having a magnetic north pole and a magnetic south pole; and a sensor associated with the base body for detecting a change in a magnetic field or a change in a magnetic field strength that results from a deformation of the elastically deformable base body. 